Wire EDM Contact Detection With Bell-Curve Speed Control
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Solution Overview
Problem
Wire electrical discharge machines face challenges in positioning the wire electrode with high precision due to delays in stopping the workpiece motion during rapid traverse, leading to potential wire electrode breakage and increased mechanical impacts during acceleration and deceleration.
Innovation Solution
The system controls servomotors to vary the relative motion speed of the wire electrode with a bell-shaped curve acceleration or deceleration until a set time constant elapses, allowing for optimal speed and acceleration during move-and-contact detection, thereby shortening positioning time and reducing mechanical impacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rapid traverse mode is used for positioning the wire electrode, then positioning speed is improved, but the wire electrode may break due to delayed stopping and increased mechanical impacts during acceleration and deceleration
Solution Approach 1:
The patent applies dynamics by making the feed speed variable rather than constant. The control device dynamically adjusts the feed speed during rapid traverse based on real-time detection of contact between the wire electrode and workpiece. When contact is detected, the system automatically transitions from high-speed rapid traverse to low-speed feed mode, preventing wire breakage while maintaining efficient positioning.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the contact state between the wire electrode and workpiece during rapid traverse. The control device receives feedback signals indicating contact and automatically adjusts the feed speed in response, switching from rapid traverse speed to feed speed to prevent wire electrode breakage while maintaining positioning efficiency.
2Reliability
If the feed speed is sharply reduced during deceleration to prevent wire breakage, then wire electrode integrity is improved, but mechanical impacts on the system increase
Solution Approach 1:
The patent applies dynamics by implementing continuous, adaptive speed adjustment rather than abrupt changes. The control device dynamically modifies the feed speed profile based on real-time contact detection, creating a smooth transition from rapid traverse to feed mode that reduces mechanical impacts while preventing wire breakage.
Solution Approach 2:
The patent applies beforehand cushioning by preparing for potential wire breakage through pre-planned speed reduction. The control device is programmed to automatically reduce feed speed when contact is detected, cushioning against the harmful effects of sudden stopping and preventing both wire breakage and excessive mechanical impacts.
3Reliability
If low feed speed mode is used to position the wire electrode, then wire electrode breakage is prevented, but positioning time increases
Solution Approach 1:
The patent applies periodic action by using two distinct speed phases: rapid traverse for the majority of the positioning distance, followed by a transition to low-speed feed mode only when contact is detected. This periodic switching between high-speed and low-speed phases minimizes positioning time while ensuring wire electrode integrity during the critical contact phase.
Solution Approach 2:
The patent applies dynamics by making the feed speed variable rather than constant. The control device dynamically adjusts the feed speed during rapid traverse based on real-time detection of contact between the wire electrode and workpiece. When contact is detected, the system automatically transitions from high-speed rapid traverse to low-speed feed mode, preventing wire breakage while maintaining efficient positioning.
Data Source
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AI summary
A wire electrical discharge machine (10) includes: a supporting member (52) for relatively moving a wire electrode (12) relative to a measurement target (W); servomotors (56X, 56Y) for moving the supporting member (52); a setting changer (70) for changing the setting of a directive speed (Vc); and a motor controller (72) that controls the servomotors (56X, 56Y) in performing move-and-contact detection for detecting contact between the wire electrode (12) and the measurement target (W) by moving the two relative to each other, so that the wire electrode (12) is moved relative to the measurement target (W) based on the directive speed (Vc) changed and specified by the setting changer (70).